Authentication is a critical mechanism for maintaining the privacy and security of a computing device or particular resources. Accordingly, a wide array of techniques and/or protocols may be implemented to verify that the user is the person he or she is claiming to be. Typical authentication systems require the user to enter a passphrase, which is compared to a passphrase stored on the computing device. For example, the user's entered passphrase may be compared with a default or pre-selected passphrase of the computing device (e.g., prior to the user's selection of an alternative passphrase) or a passphrase selected by the user (e.g., a password chosen during an enrollment process).
Voice biometrics and speaker verification are often employed to authenticate a current user of a computing device. Voice authentication permits users to “enter” a passphrase in a hands-free manner via audio input (i.e., by the user speaking into a microphone). Typical voice authentication systems require each user to enroll prior to use so that the computing device may generate a voice profile and/or other acoustic data for the particular user. For example, the computing device may generate and store a voiceprint of the user based on the user repeating the passphrase a predetermined amount of times. Then, the computing device is later able to compare the user's recitation of the passphrase to the stored voiceprint for the user. Although one objective of voice biometric authentication is oftentimes to improve the security of a system, voice biometrics are nonetheless susceptible to certain forms of security attacks (e.g., voice replay attacks).